The present invention relates to signal transmitter-receiver systems which comprise two transmitter-receiver units adapted for simultaneous bidirectional signal transmission therebetween with use of a single signal transmission line
For example in conveyors having a plurality of carriers which are self-propelled to run along a rail, there is a need for bidirectional signal transmission between the carrier and a control station on the ground.
If different signal transmission lines are provided specifically for the transmission of signals in different directions and for different signals, signals can be transmitted simultaneously and bidirectionally, whereas the system then requires a very large number of signal transmission lines for handling an increased number of signals and is therefore uneconomical.
Accordingly, a multiplex signal transmitter-receiver system has been proposed which is adapted for bidirectional transmission of a plurality of signals through a single signal line by the time division method (see Examined Japanese Patent Publication SHO 55-3857).
With the proposed system, however, transmission and receiving are effected alternatively by the time division method, such that strictly speaking, transmission and receiving are not accomplished at the same time. With an increase in the number of signals, therefore, a longer period of time is required for the bidirectional transmission of signals, consequently limiting the number of signals to be transmitted or received through the single signal transmission line.